1. Field of the Invention
The present invention relates to a small imaging apparatus capable of obtaining a sharp color image and a production method thereof. The present invention also relates to a portable device comprising the imaging apparatus. The present invention also relates to an imaging sensor for use in the imaging apparatus and a production method thereof.
2. Description of the Related Art
Portable equipments, such as a mobile phone with camera and the like, have become widespread. As the portable equipment is made smaller, thinner and more multifunctional, there is a demand for a smaller, thinner and more multifunctional imaging apparatus.
Conventionally, an imaging apparatus that uses a composite lens and an imaging sensor to take a magnified picture (zoomed picture) by mechanically moving a portion of the composite lens, has been known (e.g., see JP 2003-255225A).
FIG. 33 is a cross-sectional view of a conventional imaging apparatus.
In FIG. 33, 2001 indicates a concave lens, 2002 indicates a convex lens, 2003 indicates a filter, 2004 indicates an imaging sensor, 2005 indicates a substrate including a computing apparatus, such as a digital signal processor (DSP) or the like. The concave lens 2001, the convex lens 2002, the filter 2003, the imaging sensor 2004, and the substrate 2005 are disposed in a housing 2007 in a manner such that an optical axis 2006 of the lens system passes through substantially the center of the imaging sensor 2004. Light that is incident from a object through an opening 2007a of the housing into the housing 2007 is converged on the imaging sensor 2004 by the concave lens 2001 and the convex lens 2002. The filter 2003 prevents unnecessary light, such as infrared light and the like, from entering the imaging sensor 2004. In this case, the concave lens 2001 and the convex lens 2002 are appropriately combined in a manner such that light in a red wavelength band, light in a blue wavelength band and light in a green wavelength band that are included in light from a object are converged to the same imaging position with the same image magnification factor, thereby making it possible to prevent deterioration of a captured image due to chromatic aberration. The light converged on the imaging sensor 2004 is converted to an electrical signal by the imaging sensor 2004, and the electrical signal is processed by the computing apparatus included in the substrate 2005. In general, a sharp image can be obtained by moving a part of or the whole lens system to control focusing, depending on a distance between a object and the lens system, though no actuator is shown in FIG. 33. In addition, a magnified picture (zoomed picture) can be taken by moving the convex lens 2002 to change the magnification factor of the optical system. Moving the lenses is carried out with an actuator that is electromagnetically operated and is constructed using a permanent magnet, an electromagnet, a spring material and the like.
However, the above-described conventional imaging apparatus cannot be made thin due to use of the composite lens, disadvantageously leading to an increase in the thickness of a portable equipment with camera.